Method of producing ultraviolet radiation absorbent

ABSTRACT

An ultraviolet radiation absorbent for thermoplastic polymer materials such as polyethylene terephthalate or polycarbonate contains cyclic imino ester compound of a specified structure in an amount of over 99.5 weight % and less than 100 weight % and having an acid value in the range of 1×10 −3 –1 and/or a chlorine ion content in the range of 1×10 −1 –1×10 3  ppm.

This is a divisional of application Ser. No. 10/882,463 filed Jun. 30,2004 now U.S. Pat. No. 6,908,998, which is and is a divisional ofapplication Ser. No. 10/293,969 filed Nov. 12, 2002, now U.S. Pat. No.6,809,133 issued Oct. 26, 2004.

BACKGROUND OF THE INVENTION

This invention relates to methods of producing ultraviolet radiationabsorbents for thermoplastic polymers. Films and various kinds of moldedproducts such as boxes made of thermoplastic polymer materials undergoquality degradation such as discoloration and fading when exposed toultraviolet radiation. Different kinds of ultraviolet radiationabsorbents have therefore been in use for preventing such qualitydegradation for thermoplastic polymers as well as products made fromthem. The present invention relates to improvement in such ultravioletradiation absorbents and methods of producing such improved absorbents.

Benzophenone compounds, benzotriazole compounds and salicylic acidcompounds have been generally used as an ultraviolet radiation absorbentfor thermoplastic polymers but it has been a problem that theseabsorbents are usually low in resistance against heat. In view of thisproblem, cyclic imino ester compounds have been proposed as ultravioletradiation absorbents with improved heat resistance (U.S. Pat. No.4,446,262, Japanese Patent Publications Tokko 62-5944 and 62-31027).These absorbents are themselves more resistant against heat but stillhave the problem that, when they are added or mixed to a thermoplasticpolymer material such as polyethylene terephthalate or polycarbonate,they tend to adversely affect the original material characteristics ofthese thermoplastic polymers such as transparency. They also have theproblem of sublimating and adversely affecting the workability and theenvironmental conditions during the mixing and molding processes whenused for such thermoplastic polymer materials having high mixing andmolding temperatures. There is also the problem that they do not storewell although they may have to be stored for an extended period of timeuntil they finally come to be used.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide methods ofproducing improved ultraviolet radiation absorbents which are themselveshighly resistant against heat, capable of producing products having theoriginal material characteristics of thermoplastic polymers such astransparency when added and mixed with them without adversely affectingthe workability or the environmental conditions and capable of beingstored for an extended period of time.

The invention is based on the discovery by the present inventors as aresult of their diligent investigations that absorbents containingcyclic imino ester compounds of a specified type in a specified amountand prepared with the acid value and/or the chlorine ion contentmaintained within a specified range satisfy the aforementioned and otherobjects.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to an ultraviolet radiation absorbent forthermoplastic polymer materials containing cyclic imino ester compoundshown by Formula 1 given below in an amount of over 99.5 weight % andless than 100 weight % and prepared such that the acid value is in therange of 1×10³–1 or the chlorine ion content is in the range of1×10⁻¹–1×10³ ppm, where

The invention also relates to a method of producing an ultravioletradiation absorbent comprising Steps A, B and C, Step A being a processof separating a solid component containingN,N-bis(o-carboxyphenylterephthalamid) generated by amidation ofanthranilic acid and terephthaloyl dichloride in the presence of asolvent and an alkali, Step B being a process of separating a solidcomponent containing cyclic imino ester shown by Formula 1 generated byiminoesterification of N,N-bis(o-carboxyphenylterephthalamid) within thesolid component separated in Step A and acetic anhydride in the presenceof a solvent, and Step C being a process of processing the solidcomponent separated in Step B with an alkaline solution and furtherwashing with water to obtain an ultraviolet radiation absorbent forthermoplastic polymers containing cyclic imino ester compound shown byFormula 1 in an amount of over 99.5 weight % and less than 100 weight %t and prepared such that the acid value is in the range of 1×10⁻³–1 orthe chlorine ion content is in the range of 1×10⁻¹–1×10³ ppm.

The invention further relates to a method of producing an ultravioletradiation absorbent comprising Steps a and b, Step a being a process ofseparating a solid component cyclic imino ester compound shown byFormula 1 generated by iminoesterification of isatoic anhydride andterephthaloyl dichloride in the presence of a solvent and an alkali, andStep b being a process of processing the solid component separated inStep a with an alkaline solution and further washing with water toobtain an ultraviolet radiation absorbent for thermoplastic polymerscontaining cyclic imino ester compound shown by Formula 1 in an amountof over 99.5 weight % and less than 100 weight % and prepared such thatthe acid value is in the range of 1×10⁻³–1 or the chlorine ion contentis in the range of 1×10⁻¹–1×10³ ppm.

In the subsequent description of the invention more in detail, thecontent of cyclic imino ester compound shown by Formula 1 is the valueobtained by high performance liquid chromatography, the acid value isthe value as measured according to JIS-K0070 and the chlorine ioncontent is the value measured by the mercury thiocyanate coloringmethod.

Ultraviolet radiation absorbents of this invention are not limited bythe method of preparation. They may be prepared by (1) the method ofadjusting the content of cyclic imino ester compound shown by Formula 1and the acid value and/or the chlorine ion content of the product to bewithin the specified range in the process of producing cyclic iminoester compound shown by Formula 1 (hereinafter simply referred to as“cyclic imino ester”) as it is being produced, or (2) the method ofadjusting the content of cyclic imino ester and the acid value and/orthe chlorine ion content by adding an organic acid such as terephthalicacid, isophthalic acid, anthranilic acid and isatoic acid as an acidicsubstance and/or an inorganic salt containing chlorine atom such assodium chloride, potassium chloride and calcium chloride as a chlorineion forming compound to the produced substantially pure cyclic iminoester such that the content of cyclic imino ester, the acid value and/orthe chlorine ion content will be adjusted to be within the specifiedranges. Of these two, however, the first is preferable from the point ofview of cost of production. When the first method is used to adjust thecontent of cyclic imino ester and the acid value and/or the chlorine ioncontent of the product, this method of adjustment is not intended tolimit the scope of the invention, but the aforementioned methods throughSteps A, B and C and through Steps a and b are preferable.

The method through Steps A, B and C is explained first. Step A is aprocess of amidation of anthranilic acid and terephthaloyl dichloride inthe presence of a solvent and an alkali and separating a solid componentcontaining N,N′-bis(o-carboxyphenylterephthalamid). There is noparticular limitation as to the ratio between anthranilic acid andterephthaloyl dichloride used for the amidation process but it ispreferable to use 0.49–0.51 moles, and more preferably 0.5 moles, ofterephthaloyl dichloride per one mole of anthranilic acid. Neither isthere any particular limitation regarding the solvent but acetone,methylethyl ketone, water and their mixtures are preferred as thesolvent for anthranilic acid. As for terephthaloyl dichloride, anon-protonic solvent such as acetone and xylene is preferable. Examplesof alkali include (1) hydroxides of alkali metals such as sodiumhydroxide and potassium hydroxide, (2) carbonates of alkali metals suchas sodium carbonate and potassium carbonate, (3) hydrogencarbonates ofalkali metals such as sodium hydrogencarbonate and potassiumhydrogencarbonate and (4) organic alkalis such as pyridine, but a choiceshould be made depending on the solvent to be used such that it will bedissolved in the solvent. The amount of the alkali to be used must besufficient for completely neutralizing the hydrochloric acid produced asby-product in the amidation reaction. The reaction temperature shouldpreferably be 10–80° C. and more preferably 20–50° C. The method ofadding a solution of terephthaloyl dichloride to a liquid mixture orslurry of anthranilic acid and an alkali for the amidation ispreferable.

In Step A, N,N′-bis(o-carboxyphenylterephthalamid) is obtained by anamidation reaction of anthranilic acid and terephthaloyl dichloride. Thereaction system containing N,N′-bis(o-carboxyphenylterephthalamid) thusproduced may be in the form of a slurry or a solution, depending on thekind of the solvent and the alkali which are used. If it is in the formof a slurry, a solid component containingN,N′-bis(o-carboxyphenylterephthalamid) is separated by filtering orcentrifugation. If it is in the form of a solution, a solid componentcontaining N,N′-bis(o-carboxyphenylterephthalamid) is separated bydistilling away the solvent. The solid component thus separated may bedirectly used in Step B or may be washed with water for removing theby-product salts to a certain extent and then dried to be used in StepB.

The solid component separated in Step A is used in Step B for animinoesterification reaction betweenN,N′-bis(o-carboxyphenylterephthalamid) in the solid component andacetic anhydride in the presence of a solvent to separate a solidcomponent containing cyclic imino ester. The ratio ofN,N′-bis(o-carboxyphenylterephthalamid) in the solid component andacetic anhydride used for the iminoesterification is usually 4–20 moles,and preferably 5–10 moles, of acetic acid per one mole ofN,N′-bis(o-carboxyphenylterephthalamid). There is no particularlimitation regarding the solvent but aromatic hydrocarbons such astoluene and xylene are preferable. The reaction temperature ispreferably 100–180° C. and more preferably 110–140° C. As for the methodof the reaction, it is preferable to carry out the iminoesterificationwith reflux by adding acetic anhydride and the solvent to the solidcomponent separated in Step A.

In Step B, cyclic imino ester is generated by the iminoesterificationreaction between N,N′-bis(o-carboxyphenylterephthalamid) and aceticanhydride. The reaction system containing cyclic imino ester thusgenerated is in the form of a slurry. In Step B, a solid componentcontaining cyclic imino ester is separated from such a slurry byfiltering or centrifugation.

In Step C, the solid component separated in Step B containing cyclicimino ester is processed with an alkaline solution and washed with waterto obtain an ultraviolet radiation absorbent comprising a productprepared so as to contain cyclic imino ester in an amount of over 99.5weight % and less than 100 weight % and to have its acid value withinthe range of 1×10⁻³–1 and/or its chlorine ion content within the rangeof 1×10⁻¹–1×10³ ppm.

The method of adjusting the content of cyclic imino ester and the acidvalue of the solid component containing cyclic imino ester in Step C byan alkali treatment and containing cyclic imino ester separated in StepB by using a filter such as a Nutsche filter, an Oliver vacuum filter ora filter press or a centrifuge such as a basket type centrifuge or acentrifugal decanter is preliminarily measured. Thereafter, water,acetone or an aqueous organic solvent such as methanol or a mixturethereof is added to this solid component such that the concentration ofthe solid component will be 20–30 weight % to make a slurry. Thereafter,an alkali is added such that the acid value will change from theoriginally measured value to a resultant value in the range of 1×10³–1and an alkali treatment is effected at 10–40° C. for 1–2 hours withstirring. Next, after the solid component containing cyclic imino esteris separated from the alkali-treated slurry, the separated solidcomponent is washed with water.

There is no particular limitation as to the kind of alkali to be usedfor this alkali treatment. Examples of alkali which may be used for thispurpose include (1) alkoxides of alkali metals such as sodium methoxide,sodium ethoxide and potassium methoxide, (2) hydroxides of alkali metalssuch as sodium hydroxide and potassium hydroxide, (3) carbonates ofalkali metals such as sodium carbonate and potassium carbonate, (4)hydrogencarbonates of alkali metals such as sodium hydrogencarbonate andpotassium hydrogencarbonate, (5) ammonia water and (6) lower alkylquaternary ammonium hydroxides such as tetramethylammonium hydroxide andtetraethylammonium hydroxide. Of these, inorganic salts of alkali metalssuch as sodium hydroxide and sodium carbonate are preferable.

Neither is there any particular limitation as to the process of washingwith water. As to the quantity of water to be used, it is preferable touse about 3–20 times the weight of the solid component and morepreferably about 5–10 times. The water temperature should be preferably20–80° C.

After the solid component containing cyclic imino ester is treated withan alkali and washed with water, it is separated and dried, and itscontent of cyclic imino ester and acid value are measured in order toascertain that they are within the desired ranges. If the measurementsshow that the content of cyclic imino ester is too low or that the acidvalue is too high, the aforementioned alkali treatment and the processof washing with water are repeated.

The method of adjusting the content of cyclic imino ester and thechlorine ion content of the solid component containing cyclic iminoester in Step C by an alkali treatment and washing with water will beexplained next. First, a slurry is prepared by adding water, acetone, anaqueous solvent such as methanol or their mixture to the solid componentcontaining cyclic imino ester separated as explained above in Step Bsuch that the concentration of the solid component becomes 20–30 weight%. An appropriate amount of alkali is added to this slurry in order tomake it easier to remove chlorine ion and an alkali treatment iseffected at 10–40° C. for 1–2 hours with stirring. After the solidcomponent containing cyclic imino ester is separated from the slurrywhich has undergone this alkali treatment, it is washed with water. Thekind of alkali to be used and the conditions for the washing processwith water are as explained above.

After the solid component containing cyclic imino ester is treated withan alkali and washed with water as explained above, it is separated anddried, and the content of cyclic imino ester and the chlorine ioncontent are measured in order to ascertain that they are within thedesired ranges. If the measurement shows that the content of cyclicimino ester is too low or that the chlorine ion content is too high, theaforementioned alkali treatment and the process of washing with waterare repeated.

The method of adjusting the content of cyclic imino ester, the acidvalue and the chlorine ion content of the solid component containingcyclic imino ester in Step C by an alkali treatment and washing withwater will be explained next. First, the acid value of the solidcomponent containing cyclic imino ester separated in Step B as explainedabove is measured preliminarily. After a solvent for dissolving thealkali to be added such as water, acetone, an aqueous solvent such asmethanol or their mixture is added to make a slurry with theconcentration of the solid component equal to 20–30 weight %, the alkaliis added such that the acid value will change from the preliminarilymeasured value to a value within the range of 1×10⁻³–1 after the alkalitreatment at 10–40° C. for 1–2 hours with stirring. The solid componentcontaining cyclic imino ester is separated from the slurry which hasundergone the alkali treatment and the separated solid component iswashed with water such that its chlorine ion content comes to be withinthe range of 1×10⁻¹–1×10³ ppm. The alkali treatment as explained aboveon the solid component containing cyclic imino ester is not only for thepurpose of adjusting the content of cyclic imino ester and the acidvalue but is also important because it makes it easier to remove thechlorine ions after the washing process with water to be carried outsubsequently. The kind of alkali to be used and the conditions for thewashing process with water are as explained above.

After the solid component containing cyclic imino ester is treated withan alkali and washed with water as explained above, it is separated anddried, and its content of cyclic imino ester, acid value and chlorineion content are measured in order to ascertain that they are within thedesired ranges. If the measurements show that the content of cyclicimino ester is too low or the acid value and the chlorine ion contentare too high, the aforementioned alkali treatment and the process ofwashing with water are repeated.

After Steps A, B and C are carried out as explained above, anultraviolet radiation absorbent comprising a product which containscyclic imino ester in an amount of over 99.5 weight % and less than 100weight % and is adjusted to have its acid value with the range 1×10⁻³–1and/or its chlorine ion content within the range of 1×10⁻¹–1×10³ isobtained. In Step C, however, it is preferable to obtain a productcontaining cyclic imino ester in an amount of over 99.9 weight % andless than 100 weight % and having its acid value adjusted to3×10⁻³–1×10⁻¹ or its chlorine ion content to 1.5×10⁻¹–5×10² ppm, and iseven more preferable to obtain a product containing cyclic imino esterin an amount of over 99.9 weight % and less than 100 weight % and havingboth its acid value adjusted to 3×10⁻³–1×10⁻¹ and its chlorine ioncontent to 1.5×10⁻¹–5×10² ppm

Next, the method through Steps a and b is explained. Step a is a processof separating a solid component containing cyclic imino ester generatedby iminoesterification of isatoic anhydride and terephthaloyl dichloridein the presence of a solvent and an alkali. There is no particularlimitation as to the ratio between isatoic anhydride and terephthaloyldichloride used for the iminoesterification but it is preferable to use0.95–1.05 moles of terephthaloyl dichloride per 2 moles of isatoicanhydride. Neither is there any particular limitation regarding thesolvent. Non-protonic solvents containing nitrogen such as dimethylformaldehyde and dimethyl acetoamide, ketone solvents such as acetoneand methylethyl ketone, ether solvents such as tetrahydrofuran anddioxane, and their mixtures are examples that may be used but acetone ispreferred. Neither is there any particular limitation regarding thealkali. Examples include (1) hydroxides of alkali metals such as sodiumhydroxide and potassium hydroxide, (2) lower alkyl quaternary ammoniumhydroxides such as tetramethylammonium hydroxide and tetraethylammoniumhydroxide and (3) organic alkalis such as pyridine, but pyridine ispreferred. An appropriate kind of alkali should be used, depending onthe selected kind of solvent, so as to be dissolved in the selected kindof solvent. The amount of the alkali to be used is preferably selectedsuch that the hydrochloric acid generated as by-product in theiminoesterification will be 100% neutralized. The reaction temperatureshould preferably be 10–80° C. and more preferably 20–50° C. As for themethod of the reaction, it is preferable to add a solution ofterephthaloyl dichloride to a mixed solution or slurry of isatoicanhydride for iminoesterification.

In Step a, cyclic imino ester is generated by iminoesterification ofisatoic anhydride and terephthaloyl dichloride. The reaction systemcontaining cyclic imino ester thus generated is either in the form or aslurry or in the form of a solution, depending on the kinds of thesolvent and the alkali which have been used. If it is in the form of aslurry, the solid component containing cyclic imino ester is separatedby filtering or by centrifugation. If it is in the form of a solution,the solvent is distilled away to separate the solid component containingcyclic imino ester. The solid component thus separated may be directlyused in Step b or may be washed with water in order to remove by-productsalts to a certain extent and dried before being used in Step b.

In Step b, the solid component containing cyclic imino ester separatedin Step a is treated with an alkali and then washed with water to obtainan ultraviolet radiation absorbent comprising a product containingcyclic imino ester in an amount of over 99.5 weight % and less than 100weight % and prepared such that its acid value is in the range of1×10⁻³–1 and/or that its chlorine ion content is in the range of1×10⁻¹–1×10³ ppm. Thus, Step b is the same as aforementioned Step C.

In this manner, an ultraviolet radiation absorbent, comprising a productcontaining cyclic imino ester in an amount of over 99.5 weight % andless than 100 weight % and prepared such that its acid value is in therange of 1×10⁻³–1 and/or that its chlorine ion content is in the rangeof 1×10⁻¹–1×10³ ppm, is obtained through Steps a and b. In Step b,however, it is preferable to obtain a product containing cyclic iminoester in an amount of over 99.9 weight % and less than 100 weight % andhaving an acid value of 3×10⁻³–1×10⁻¹ or a chlorine ion content of1.5×10⁻¹–5×10² ppm, and it is even more preferable to obtain a productcontaining cyclic imino ester by over 99.9 weight % and less than 100weight % and having both an acid value of 3×10⁻³–1×10⁻¹ and a chlorineion content of 1.5×10⁻¹–5×10² ppm.

The invention does not place any particular limitation on the kind ofthermoplastic polymers to which ultraviolet radiation absorbents asdescribed above should be applied. Examples of thermoplastic polymers towhich they may be applied include (1) thermoplastic polyesters such aspolyethylene terephthalate, polyethylene naphthalate and polybutyleneterephthalate, (2) polycarbonates, (3) styrene polymers such aspolystyrene, styrene-acrylnitrile-butadien copolymers and high-impactpolystyrene, (4) acryl polymers, (5) amid polymers, (6) polyphenyleneether, (7) polyolefins such as polyethylene, polypropylene and vinylpolychloride, (8) polyoxymethylene, (9) polyphenylene sulfide, (10)lactic acid polymers and (11) mixtures of these thermoplastic polymers.Absorbents according to this invention are particularly effective whenadded to and mixed with polyethylene terephthalate and polycarbonateswhich have high transparency and require a high mixing temperature and ahigh molding temperature.

Ultraviolet radiation absorbents for thermoplastic polymers embodyingthis invention, having the content of cyclic imino ester and acid valueand/or chlorine ion content adjusted within a specified range, arethemselves highly resistant against heat and can be added to and mixedwith thermoplastic polymers such as polyethylene terephthalate andpolycarbonates requiring a high mixing temperature and a high moldingtemperature to produce molded products having the same high transparencyoriginally possessed by these thermoplastic polymers. Those having theacid value adjusted to a specified range, in particular, do notadversely affect the workability or the environmental condition in themixing and molding processes even when added to and mixed withthermoplastic polymers such as polyethylene terephthalate andpolycarbonates requiring a high mixing temperature and a high moldingtemperature. Those having the chlorine ion content adjusted to within aspecified range store well. Those having the acid value adjusted towithin a specified range and the chlorine ion content adjusted to withina specified range do not adversely affect the workability or theenvironmental condition in the mixing and molding processes even whenadded to and mixed with thermoplastic polymers such as polyethyleneterephthalate and polycarbonates having a high mixing temperature and ahigh molding temperature and also store well.

The invention does not particularly limit the amount of the absorbent tobe used. When it is applied to thermoplastic polymers, the ratio isusually 0.1–5 weight parts to 100 weight parts of thermoplasticpolymers.

The invention is described next with reference to the following twelveembodiments.

(1) Ultraviolet radiation absorbent containing cyclic imino ester by99.99 weight % and having acid value adjusted to 1.5×10⁻³.

(2) Ultraviolet radiation absorbent containing cyclic imino ester by99.99 weight % and having acid value adjusted to 4×10⁻³.

(3) Ultraviolet radiation absorbent containing cyclic imino ester by99.95 weight % and having acid value adjusted to 8×10⁻².

(4) Ultraviolet radiation absorbent containing cyclic imino ester by99.65 weight % and having acid value adjusted to 9×10⁻¹.

(5) Ultraviolet radiation absorbent containing cyclic imino ester by99.99 weight % and having chlorine ion content adjusted to 1.5×10⁻¹ ppm.

(6) Ultraviolet radiation absorbent containing cyclic imino ester by99.99 weight % and having chlorine ion content adjusted to 2×10⁻¹ ppm.

(7) Ultraviolet radiation absorbent containing cyclic imino ester by99.90 weight % and having chlorine ion content adjusted to 4×10² ppm.

(8) Ultraviolet radiation absorbent containing cyclic imino ester by99.94 weight % and having chlorine ion content adjusted to 9.5×10² ppm.

(9) Ultraviolet radiation absorbent containing cyclic imino ester by99.96 weight % and having acid value adjusted to 3×10⁻³ and chlorine ioncontent adjusted to 1.5×10⁻¹ ppm.

(10) Ultraviolet radiation absorbent containing cyclic imino ester by99.94 weight % and having acid value adjusted to 5×10³ and chlorine ioncontent adjusted to 3×10⁻¹ ppm.

(11) Ultraviolet radiation absorbent containing cyclic imino ester by99.92 weight % and having acid value adjusted to 9×10⁻² and chlorine ioncontent adjusted to 3×10² ppm.

(12) Ultraviolet radiation absorbent containing cyclic imino ester by99.71 weight % and having acid value adjusted to 8×10⁻¹ and chlorine ioncontent adjusted to 9×10² ppm.

The invention is described next by way of examples but it goes withoutsaying that these examples are not intended to limit the scope of theinvention. In what follows, “part” will mean “weight part” and “%” willmean “weight %”.

Part 1 (Preparation of Ultraviolet Radiation Absorbents forThermoplastic Polymers: No. 1) TEST EXAMPLE 1

Anthranilic acid 13.7 g (0.1 moles), anhydrous sodium carbonate 5.19 g(0.049 moles) and water 100 ml were placed in a flask with four openingsprovided with a thermometer, a stirrer, a reflux cooler and a dropperfunnel and the mixture was dissolved with stirring for 10 minutes. Aftera solution obtained by dissolving terephthaloyl dichloride 10.2 g (0.05moles) in acetone 300 ml was dropped into this flask by means of thedropper funnel over one hour at room temperature, a slurry with solidcomponent containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 19.9 g was obtained. The dried solidcomponent 19.9 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 100 ml and dried, a solid component17.3 g (acid value 2.1) containing cyclic imino ester was obtained.Finally, this solid component 17 g and water 68 g were placed in theflask and 1% aqueous solution of sodium hydroxide 2.50 g was added withstirring and an alkali treatment was effected at 25° C. for 30 minuteswith stirring. The alkali-treated solid component was filtered out andwashed with warm water 160 g at 60° C. The washed solid component wasdried for 2 hours with a hot-air drier at 100° C. to obtain yellowishpowder 16.6 g. This yellowish powder was analyzed and found to containcyclic imino ester by 99.99%, and its acid value was 1.5×10⁻³. This willbe referred to as Absorbent (P-1). The content of cyclic imino ester wasmeasured by high performance liquid chromatography using chloroform asthe elution liquid and a UV detector for detection.

TEST EXAMPLE 2

Anthranilic acid 13.7 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 1, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropper funnel over one hour at room temperature, a slurry withsolid component containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 18.0 g was obtained. The dried solidcomponent 18.0 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 100 ml and dried, a solid component15.0 g (acid value 1.3) containing cyclic imino ester was obtained.Finally, this solid component 14 g and methanol 68 g were placed in theflask and 1% solution of sodium methoxide methanol 1.71 g was added withstirring and an alkali treatment was effected at 25° C. for 30 minuteswith stirring. The alkali-treated solid component was filtered out andwashed with warm water 140 g at 40° C. The washed solid component wasdried for 2 hours with a hot-air drier at 100° C. to obtain yellowishpowder 13.5 g. This yellowish powder was analyzed and found to containcyclic imino ester by 99.99%, and its acid value was 4×10⁻³. This willbe referred to as Absorbent (P-2).

TEST EXAMPLE 3

Isatoic anhydride 16.3 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 1, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropper funnel over one hour at room temperature, a slurry withsolid component containing cyclic imino ester was obtained byiminoesterification for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 15.9 g (acid value 3.0) containing cyclicimino ester was obtained. The dried solid component 15 g and water 48 gwere placed in the flask and 1% aqueous solution of sodium carbonate4.16 g was added with stirring and an alkali treatment was effected at30° C. for 30 minutes with stirring. The alkali-treated solid componentwas filtered out and washed with warm water 100 g at 60° C. The washedsolid component was dried for 2 hours with a hot-air drier at 100° C. toobtain yellowish powder 14.5 g. This yellowish powder was analyzed andfound to contain cyclic imino ester by 99.95%, and its acid value was8×10⁻². This will be referred to as Absorbent (P-3).

TEST EXAMPLE 4

Anthranilic acid 13.7 g (0.1 moles), potassium hydroxide 5.32 g (0.095moles) and water 100 ml were placed in a flask with four openings as inTest Example 1, and the mixture was dissolved with stirring for 10minutes. After a solution obtained by dissolving terephthaloyldichloride 10.2 g (0.05 moles) in acetone 200 ml was dropped into thisflask by means of the dropper funnel over one hour at room temperature,a slurry with solid component containingN,N′-bis(o-carboxyphenylterephthalamid) was obtained by amidation forone hour with reflux. A solid component was separated from this slurryand after it was washed with water 300 ml and dried, a dried solidcomponent 19.8 g was obtained. The dried solid component 19.8 g, aceticanhydride 102 g (1 mole) and toluene 100 ml were placed in the flask foriminoesterification with reflux for 6 hours, and after it was cooleddown to room temperature, a solid component 15.5 g (acid value 5.1)containing cyclic imino ester was obtained. This dried solid component15 g and water 35 g were placed in the flask and 1% aqueous solution ofpotassium hydroxide 7.50 g was added with stirring and an alkalitreatment was effected at 25° C. for 30 minutes with stirring. Thealkali-treated solid component was filtered out and washed with warmwater 160 g at 60° C. The washed solid component was dried for 2 hourswith a hot-air drier at 100° C. to obtain yellowish powder 14.2 g. Thisyellowish powder was analyzed and found to contain cyclic imino ester by99.65%, and its acid value was 9×10⁻¹. This will be referred to asAbsorbent (P-4).

COMPARISON EXAMPLE 1

Absorbent (P-1) obtained in Test Example 1 10 g and 1×10⁻²% aqueoussolution of sodium hydroxide 1000 ml were placed in a beaker. After itwas stirred for one hour with a mixer, a solid component was filtered.The filtered solid component and water 1000 ml were placed in a beaker,and after it was stirred for one hour with a mixer, a solid componentwas filtered. This routine was repeated three times and the solidcomponent thus obtained was dried for one hour at 100° C. to obtainyellowish powder. This yellowish powder was analyzed and found tocontain cyclic imino ester by 100.00%, and its acid value was 6×10⁻⁴.This will be referred to as Absorbent (R-1).

COMPARISON EXAMPLE 2

Yellowish powder 16.9 g was obtained in the same way as in Test Example1 except that the alkali treatment was dispensed with. This yellowishpowder was analyzed and found to contain cyclic imino ester by 99.41%,and its acid value was 1.3. This will be referred to as Absorbent (R-2).

Part 2 (Preparation of Ultraviolet Radiation Absorbents forThermoplastic Polymers: No. 2) TEST EXAMPLE 5

Anthranilic acid 13.7 g (0.1 moles), anhydrous sodium carbonate 5.19 g(0.049 moles) and water 100 ml were placed in a flask with four openingsprovided with a thermometer, a stirrer, a reflux cooler and a dropperfunnel and the mixture was dissolved with stirring for 10 minutes. Aftera solution obtained by dissolving terephthaloyl dichloride 10.2 g (0.05moles) in acetone 300 ml was dropped into this flask by means of thedropper funnel over one hour at room temperature, a slurry with solidcomponent containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 19.7 g was obtained. The dried solidcomponent 19.7 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 100 ml and dried, a solid component17.2 g containing cyclic imino ester was obtained. Finally, this solidcomponent 17 g and water 68 g were placed in the flask and 1% aqueoussolution of sodium hydroxide 2.42 g was added with stirring and analkali treatment was effected at 25° C. for 30 minutes with stirring.The alkali-treated solid component was filtered out and washed with warmwater 160 g at 60° C. The washed solid component was dried for 2 hourswith a hot-air drier at 100° C. to obtain yellowish powder 16.7 g. Thisyellowish powder was analyzed and found to contain cyclic imino ester by99.99%, and its chlorine ion content was 1.5×10⁻¹ ppm. This will bereferred to as Absorbent (P-5).

The chlorine ion content was measured as follows by the mercurythiocyanate coloring method. Absorbent (P-5) 10 g is accurately measuredand placed in a triangular flask together with ion exchange water 10 ml.An air cooler tube is attached to this flask and it is heated for onehour at 90° C. while shaking it from time to time. After it is cooled tothe room temperature, a filtrate is obtained by filtering. The filtrate10 ml is collected in a test tube, a nitric acid solution of ferricnitrate (obtained by dissolving 200 g of ferric nitrate in 500 ml of 5Nnitric acid) 2 ml and a mercuric thiocyanate solution (obtained bydissolving 1 g of mercuric thiocyanate in 250 ml of methyl alcohol) areadded and it is shaken together. Ten minutes after the addition of themercuric thiocyanate solution, the absorbance at 460 nm is measured bymeans of a spectrophotometer. Separately, a calibration line is preparedby using a standard liquid of sodium chloride of the optical grade andthe chlorine ion content of Absorbent (P-5) is obtained from thiscalibration line.

TEST EXAMPLE 6

Anthranilic acid 13.7 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 5, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropping funnel over one hour at room temperature, a slurry withsolid component containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasfiltered out from this slurry and after it was washed with water 300 mland dried, a dried solid component 17.8 g was obtained. The dried solidcomponent 17.8 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 100 ml and dried, a solid component14.7 g containing cyclic imino ester was obtained. Finally, this solidcomponent 14 g and methanol 68 g were placed in the flask and 1%solution of sodium methoxide methanol 1.71 g was added with stirring andan alkali treatment was effected at 25° C. for 30 minutes with stirring.The alkali-treated solid component was filtered out and washed with warmwater 140 g at 40° C. The washed solid component was dried for 2 hourswith a hot-air drier at 100° C. to obtain yellowish powder 13.6 g. Thisyellowish powder was analyzed and found to contain cyclic imino ester by99.99%, and its chlorine ion content was 2×10⁻¹ ppm. This will bereferred to as Absorbent (P-6).

TEST EXAMPLE 7

Isatoic anhydride 16.3 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 5, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropping funnel over one hour at room temperature, a slurry withsolid component containing cyclic imino ester was obtained byiminoesterification for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 16.0 g containing cyclic imino ester wasobtained. The dried solid component 15 g and water 48 g were placed inthe flask and 1% aqueous solution of sodium carbonate 4.24 g was addedwith stirring and an alkali treatment was effected at 30° C. for 30minutes with stirring. The alkali-treated solid component was filteredout and washed with warm water 100 g at 60° C. The washed solidcomponent was dried for 2 hours with a hot-air drier at 100° C. toobtain yellowish powder 14.7 g. This yellowish powder was analyzed andfound to contain cyclic imino ester by 99.90%, and its chlorine ioncontent was 4×10² ppm. This will be referred to as Absorbent (P-7).

TEST EXAMPLE 8

Anthranilic acid 13.7 g (0.1 moles), potassium hydroxide 5.32 g (0.095moles) and water 100 ml were placed in a flask with four openings as inTest Example 5, and the mixture was dissolved with stirring for 10minutes. After a solution obtained by dissolving terephthaloyldichloride 10.2 g (0.05 moles) in acetone 200 ml was dropped into thisflask by means of the dropper funnel over one hour at room temperature,a slurry with solid component containingN,N′-bis(o-carboxyphenylterephthalamid) was obtained by amidation forone hour with reflux. A solid component was separated from this slurryand after it was washed with water 300 ml and dried, a dried solidcomponent 19.7 g was obtained. The dried solid component 19.7 g, aceticanhydride 102 g (1 mole) and toluene 100 ml were placed in the flask foriminoesterification with reflux for 6 hours, and after it was cooleddown to room temperature, the solid component was filtered out. Afterthis filtered solid component was washed with acetone 100 ml and dried,a solid component 15.3 g containing cyclic imino ester was obtained.This dried solid component 15 g and water 35 g were placed in the flaskand 1% aqueous solution of potassium hydroxide 7.46 g was added withstirring and an alkali treatment was effected at 25° C. for 30 minuteswith stirring. The alkali-treated solid component was filtered out andwashed with warm water 160 g at 60° C. The washed solid component wasdried for 2 hours with a hot-air drier at 100° C. to obtain yellowishpowder 14.5 g. This yellowish powder was analyzed and found to containcyclic imino ester by 99.94%, and its chlorine ion content was 9.5×10²ppm. This will be referred to as Absorbent (P-8).

COMPARISON EXAMPLE 3

Absorbent (P-5) obtained in Test Example 5 10 g and 1×10⁻²% aqueoussolution of sodium hydroxide 1000 ml were placed in a beaker. After itwas stirred for one hour with a mixer, a solid component was filtered.The filtered solid component and water 1000 ml were placed in a beaker,and after it was stirred for one hour with a mixer, a solid componentwas filtered. This routine was repeated three times and the solidcomponent thus obtained was dried for one hour at 100° C. to obtainyellowish powder. This yellowish powder was analyzed and found tocontain cyclic imino ester by 100.00%, and its chlorine ion content was5×10⁻² ppm. This will be referred to as Absorbent (R-3).

COMPARISON EXAMPLE 4

Yellowish powder 17.0 g was obtained in the same way as in Test Example5 except that the alkali treatment was dispensed with. This yellowishpowder was analyzed and found to contain cyclic imino ester by 98.79%,and its chlorine ion content was 2×10⁻³ ppm. This will be referred to asAbsorbent (R-4).

Part 3 (Preparation of Ultraviolet Radiation Absorbents forThermoplastic Polymers: No. 3) TEST EXAMPLE 9

Anthranilic acid 13.7 g (0.1 moles), anhydrous sodium carbonate 5.19 g(0.049 moles) and water 100 ml were placed in a flask with four openingsprovided with a thermometer, a stirrer, a reflux cooler and a dropperfunnel and the mixture was dissolved with stirring for 10 minutes. Aftera solution obtained by dissolvingterephthaloyl dichloride 10.2 g (0.05moles) in acetone 300 ml was dropped into this flask by means of thedropper funnel over one hour at room temperature, a slurry with solidcomponent containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 19.7 g was obtained. The dried solidcomponent 19.7 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 10 ml and dried, a solid component17.4 g (acid value 2.3) containing cyclic imino ester was obtained.Finally, this solid component 17 g and water 68 g were placed in theflask and 1% aqueous solution of sodium hydroxide 2.79 g was added withstirring and an alkali treatment was effected at 25° C. for 30 minuteswith stirring. The alkali-treated solid component was filtered out andwashed with warm water 160 g at 60° C. After the washed solid componentwas dehydrated, it was dried for 2 hours with a hot-air drier at 100° C.to obtain yellowish powder 16.5 g. This yellowish powder was analyzedand found to contain cyclic imino ester by 99.96%. Its acid value was3×10⁻³ and its chlorine ion content was 1.5×10⁻¹ ppm. This will bereferred to as Absorbent (P-9).

TEST EXAMPLE 10

Anthranilic acid 13.7 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 9, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropper funnel over one hour at room temperature, a slurry withsolid component containing N,N′-bis(o-carboxyphenylterephthalamid) wasobtained by amidation for one hour with reflux. A solid component wasfiltered out from this slurry and after it was washed with water 300 mland dried, a dried solid component 17.9 g was obtained. The dried solidcomponent 17.9 g, acetic anhydride 102 g (1 mole) and toluene 100 mlwere placed in the flask with four openings for iminoesterification withreflux for 6 hours, and after it was cooled down to room temperature,the solid component was filtered out. After this filtered solidcomponent was washed with acetone 100 ml and dried, a solid component15.1 g (acid value 1.4) containing cyclic imino ester was obtained.Finally, this solid component 14 g and methanol 68 g were placed in theflask and 1% solution of sodium methoxide methanol 1.88 g was added withstirring and an alkali treatment was effected at 25° C. for 30 minuteswith stirring. The alkali-treated solid component was filtered out andwashed with warm water 140 g at 40° C. After the washed solid componentwas dehydrated, it was dried for 2 hours with a hot-air drier at 100° C.to obtain yellowish powder 13.5 g. This yellowish powder was analyzedand found to contain cyclic imino ester by 99.94%. Its acid value was5×10⁻³ and its chlorine ion content was 3×10⁻¹ ppm. This will bereferred to as Absorbent (P-10).

TEST EXAMPLE 11

Isatoic anhydride 16.3 g (0.1 moles), pyridine 7.74 g (0.098 moles) andacetone 200 ml were placed in a flask with four openings as in TestExample 9, and the mixture was dissolved with stirring for 10 minutes.After a solution obtained by dissolving terephthaloyl dichloride 10.2 g(0.05 moles) in acetone 100 ml was dropped into this flask by means ofthe dropper funnel over one hour at room temperature, a slurry withsolid component containing cyclic imino ester was obtained byiminoesterification for one hour with reflux. A solid component wasseparated from this slurry and after it was washed with water 300 ml anddried, a dried solid component 16.2 g (acid value 3.2) containing cyclicimino ester was obtained. The dried solid component 15 g and water 48 gwere placed in the flask and 1% aqueous solution of sodium carbonate4.54 g was added with stirring and an alkali treatment was effected at30° C. for 30 minutes with stirring. The alkali-treated solid componentwas filtered out and washed with warm water 130 g at 60° C. After thewashed solid component was dehydrated, it was dried for 2 hours with ahot-air drier at 100° C. to obtain yellowish powder 14.3 g. Thisyellowish powder was analyzed and found to contain cyclic imino ester by99.92%. Its acid value was 9×10⁻² and its chlorine ion content was 3×10²ppm. This will be referred to as Absorbent (P-11).

TEST EXAMPLE 12

Anthranilic acid 13.7 g (0.1 moles), potassium hydroxide 5.32 g (0.095moles) and water 100 ml were placed in a flask with four openings as inTest Example 9, and the mixture was dissolved with stirring for 10minutes. After a solution obtained by dissolving terephthaloyldichloride 10.2 g (0.05 moles) in acetone 200 ml was dropped into thisflask by means of the dropper funnel over one hour at room temperature,a slurry with solid component containingN,N′-bis(o-carboxyphenylterephthalamid) was obtained by amidation forone hour with reflux. A solid component was separated from this slurryand after it was washed with water 300 ml and dried, a dried solidcomponent 19.8 g was obtained. The dried solid component 19.8 g, aceticanhydride 102 g (1 mole) and toluene 100 ml were placed in the flask foriminoesterification with reflux for 4 hours, and after it was cooleddown to room temperature, a solid component was filtered. After thefiltered solid component was washed with acetone 100 ml, it was dried toobtain a solid component 15.6 g (acid value 5.1) containing cyclic iminoester was obtained. This dried solid component 15 g and water 35 g wereplaced in the flask and 1% aqueous solution of potassium hydroxide 7.65g was added with stirring and an alkali treatment was effected at 25° C.for 30 minutes with stirring. The alkali-treated solid component wasfiltered out and washed with warm water 100 g at 60° C. After the washedsolid component was dehydrated, it was dried for 2 hours with a hot-airdrier at 100° C. to obtain yellowish powder 14.35 g. This yellowishpowder was analyzed and found to contain cyclic imino ester by 99.71%.Its acid value was 8×10⁻¹ and its chlorine ion content was 9×10² ppm.This will be referred to as Absorbent (P-12).

COMPARISON EXAMPLE 5

Absorbent (P-9) obtained in Test Example 9 10 g and 1×10⁻²% aqueoussolution of sodium hydroxide 1000 ml were placed in a beaker. After itwas stirred for one hour with a mixer, a solid component was filtered.The filtered solid component and water 1000 ml were placed in a beaker,and after it was stirred for one hour with a mixer, a solid componentwas filtered. This routine was repeated three times and the solidcomponent thus obtained was dried for one hour at 100° C. to obtainyellowish powder. This yellowish powder was analyzed and found tocontain cyclic imino ester by 100.00%. Its acid value was 6×10⁻⁴ and itschlorine ion content was 5×10⁻² ppm. This will be referred to asAbsorbent (R-5).

COMPARISON EXAMPLE 6

Yellowish powder 17.0 g was obtained in the same way as in Test Example9 except that the alkali treatment was dispensed with. This yellowishpowder was analyzed and found to contain cyclic imino ester by 99.20%.Its acid value was 1.4 and its chlorine ion content was 1.8×10³ ppm.This will be referred to as Absorbent (R-6).

Part 4 (Evaluation on Ultraviolet Radiation Absorption)

Each of the ultraviolet radiation absorbents 1.0 mg prepared in Parts 1,2 and 3 was dissolved in 200 ml of 1,1,2,2-tetrachlorethane of theoptical grade and transparency at 350 nm measured by using a UV-Visspectrophotometer (U2000 produced by Hitachi, Ltd.) was evaluatedaccording to the following standard.

A: Transparency less than 25%

B: Transparency greater than 25% but less than 26%

C: Transparency greater than 26%

The results are shown in Table 1.

Part 5 (Evaluation of Shelf Life)

Ultraviolet radiation absorbents 10 g prepared in Parts 2 and 3 wereeach placed in a receptacle and stored for six months inside a humiditycontrollable incubator at temperature 40° C. and humidity 50%. The acidvalue was measured before and after the storage period and the increasewas evaluated according to the following standard:

A: Increase in acid value less than 1×10⁻².

B: Increase in acid value greater than 1×10⁻² and less than 1×10⁻¹.

C: Increase in acid value greater than 1×10⁻¹ and less than 1.

D: Increase in acid value greater than 1.

Part 6 (Evaluation when Absorbents are Added and Mixed with PolyethyleneTerephthalate)

Ultraviolet radiation absorbents prepared in Parts 1, 2 and 3 wereevaluated regarding resistance against heat and transparency when addedto and mixed with polyethylene terephthalate with intrinsic viscosity0.70. Those prepared in Parts 1 and 3 were evaluated for workability insimilar situations.

For evaluating resistance against heat, 100 parts of polyethyleneterephthalate chips and 2 parts of each of the absorbents prepared inParts 1–3 were subjected to a dry blending process and extruded while adouble-axis extruder was used to mix them together at 280° C. After themixture was cooled and made into pellets, they were dried in vacuum. Thevacuum-dried pellets 10 g were put inside a test tube to prepare SamplesB obtained by heating and melting for 10 minutes and Samples T obtainedby heating and melting for 60 minutes. Both Samples B and T were checkedvisually and evaluated according to the following standard:

A: No difference between B and T and no abnormalities such as burns wereobserved on T.

B: T is somewhat more yellowish than B but no abnormalities such asburns were observed on T.

C: T is clearly more yellowish than B and burns were observed on partsof T.

For evaluating transparency, 100 parts of polyethylene terephthalatechips and 2 parts each of the absorbents prepared in Parts 1–3 weresubjected to a dry blending process and extruded from a T-die while adouble-axis extruder was used to mix them together at 280° C. and cooledby means of a cooling roller at about 50° C. to produce non-crystallinesheets of thickness about 1 mm. Blank sheets were separately prepared inthe same manner except without blending the ultraviolet radiationabsorbents. Evaluation of transparency was carried out according to thefollowing standard:

A: As transparent as the blanks

B: Very little more cloudy than the blanks

C: A little more cloudy than the blanks

D: Definitely more cloudy than the blanks

For the evaluation of workability, 100 parts of polyethyleneterephthalate chips and 2 parts each of the absorbents prepared in Parts1 and 3were subjected to a dry blending process. Extrusion was repeatedcontinuously for 6 hours while a double-axis extruder was used to mixthem together at 280° C. Presence or absence of deposits at the ventopening of the extruder was visually checked one hour, 3 hours, and 6hours after the starting of the extrusion and workability was evaluatedaccording to the following standard:

A: Deposits not observed after 6 hours

B: Deposits not observed after 3 hours but observed after 6 hours

C: Deposits not observed after one hour but observed after 3 hours

D: Deposits observed after one hour

Part 7 (Evaluation when Absorbents are Added and Mixed withPolycarbonate)

Ultraviolet radiation absorbents prepared in Parts 1, 2 and 3 wereevaluated regarding resistance against heat and transparency when addedto and mixed with polycarbonate chips (Panlite, produced by TeijinChernicals, Ltd). Those prepared in Parts 1 and 3 were evaluated forworkability in similar situations.

For evaluating resistance against heat, 100 parts of polycarbonate chipsand 2 parts each of the absorbents prepared in Parts 1–3 were subjectedto a dry blending process and a double-axis extruder was used to mixthem together at 290° C. After the extrusion, it was cooled with water,made into pellets and dried in vacuum for 5 hours at 100° C. Evaluationswere made as in Part 6.

For evaluating transparency, 100 parts of polycarbonate chips and 2parts each of the absorbents prepared in Parts 1–3 were subjected to adry blending process and a double-axis extruder was used to mix themtogether at 290° C. and they were extruded from a T-die and cooled bymeans of a cooling roller at about 50° C. to produce sheets of thicknessabout 1 mm. Evaluations were made as in Part 6.

For evaluating workability, 100 parts of polycarbonate chips and 2 partseach of the absorbents prepared in Parts 1 and 3 were subjected to a dryblending process. Extrusion was repeated continuously for 6 hours whilea double-axis extruder was used to mix them together at 290° C.Evaluations were made as in Part 6.

TABLE 1 Absorbent Kind/Con- Chlorine Evaluations centration Acid ioncontent PET PC (%) value (ppm) AB SL RH WK TR RH WK TR Test  1 P-1/99.991.5 × 10⁻³   — A — B B A B B B  2 P-2/99.99 4 × 10⁻³ — A — B A A B B A 3 P-3/99.95 8 × 10⁻² — A — B A A B A A  4 P-4/99.65 9 × 10⁻¹ — B — B AB B A B Comp  1 R-1/100.00 6 × 10⁻⁴ — A — B D D B D D  2 R-2/99.41 1.3 —C — D A D D A D Test  5 P-5/99.99 — 1.5 × 10⁻¹ A B B — A B — A  6P-6/99.99 —   2 × 10⁻¹ A B B — A B — A  7 P-7/99.90 —   4 × 10² A A B —A B — A  8 P-8/99.94 — 9.5 × 10² B A B — B B — B Comp  3 R-3/100.00 —  5 × 10⁻² A D B — D B — D  4 R-4/98.79 —   2 × 10³ C A D — D D — D Test 9 P-9/99.96 3 × 10⁻³ 1.5 × 10⁻¹ A B B A B B A B 10 P-10/99.94 5 × 10⁻³  3 × 10⁻¹ A B B A A B A A 11 P-11/99.92 9 × 10⁻²   3 × 10² A A B B A BB A 12 P-12/99.71 8 × 10⁻¹   9 × 10² B A B B B B B B Comp  5 R-5/100.006 × 10⁻⁴   5 × 10⁻² A D B D D B D D  6 R-6/99.20 1.4 1.8 × 10³ C A D A DD A D In Table 1: Test: Test Example Comp: Comparison ExampleConcentration: Concentration (%) of cyclic imino ester in ultravioletradiation absorbent for thermoplastic polymers PET: Polyethyleneterephthalate PC: Polycarbonate AB: Absorbence of ultraviolet radiationSL: Shelf life RH: Resistance against heat WK: Workability TR:Transparency

As can be understood from above, each of the absorbents of Test Examples1–12 satisfies the requirements on the ability to absorb ultravioletradiation, resistance against heat and transparency and each of theabsorbents of Test Examples 1–4 and 9–12 also satisfy the requirement onworkability. Each of the absorbents of Test Examples 5–12 also has agood shelf life. In particular, those of Test Examples 9–11 withconcentration of cyclic imino ester greater than 99.9% and less than100%, having an acid value in the range of 3×10⁻³–1×10⁻¹ and a chlorineion content within the range of 1.5×10⁻¹–5×10² ppm are excellent. Bycontrast, Comparison Examples 1, 3 and 5 are substantially purely cyclicimino ester without hardly any acidic substance which affects the acidvalue or any chlorine ion, being not good in transparency and poor ineither workability or shelf life. Comparison Examples 2, 4 and 6 containrelatively large quantities of acidic substance and chlorine ions andthe content of cyclic imino ester is accordingly lower. They areinferior in the ability to absorb ultraviolet radiation and also poor inresistance against heat and transparency.

In summary, the absorbents according to this invention are themselvessuperior in resistance against heat and capable of being added to andmixed with thermoplastic polymers such as polyethylene terephthalate orpolycarbonate to obtain molded products with the same transparentcharacteristic of the thermoplastic polymers, not adversely affectingthe environmental conditions during the mixing and molding processes andthemselves having a good shelf life.

1. A method of producing an ultraviolet radiation absorbent compositionfor thermoplastic polymers, said method comprising Step a and Step b;said Step a being a process of iminoesterification of isatoic anhydrideand terephthaloyl dichloride in presence of a solvent and an alkali,followed by separating from the reaction mixture a cyclic iminoestercompound solid component shown by Formula 1 given below

said Step b being a process of treating the solid component separated insaid Step a with an alkaline solution and further washing with water toobtain the ultraviolet radiation absorbent composition for thermoplasticpolymers containing cyclic imino ester compound shown by Formula 1 in anamount of over 99.5 weight % and less than 100 weight % and having anacid value in the range of 1×10⁻³–1 KOHmg/g and a chlorine ion contentin the range of 1×10⁻¹–1×10⁻³ ppm.
 2. The method of claim 1 wherein saidStep b the ultraviolet radiation absorbent for thermoplastic polymers isobtained containing cyclic imino ester compound shown by Formula 1 in anamount of over 99.9 weight % and less than 100 weight % and having anacid value in the range of 3×10⁻³–1×10⁻¹ KOHmg/g and a chlorine ioncontent in the range of 1.5×10⁻¹–5×10² ppm.